The invention relates to a refiner blade comprising a blade surface for defibrating a lignocellulose-containing material, the blade surface comprising blade bars and blade grooves provided therebetween.
The invention also relates to a blade segment of a refiner blade, comprising a blade surface for defibrating a lignocellulose-containing material, the blade surface comprising blade bars and blade grooves provided therebetween.
The invention relates to a refiner blade comprising a blade surface for defibrating a lignocellulose-containing material, the blade surface comprising first blade bars and first blade grooves provided therebetween, and the first blade bars comprising second blade bars and second blade grooves provided therebetween and arranged to connect the first blade grooves.
The invention further relates to a blade segment of a refiner blade, comprising a blade surface for defibrating a lignocellulose-containing material, the blade surface comprising first blade bars and first blade grooves provided therebetween, the first blade bars comprising second blade bars and second blade grooves provided therebetween and arranged to connect the first blade grooves.
The invention still further relates to a method of forming blade grooves in a blade surface of a refiner blade or a refiner blade segment, the blade surface being provided for defibrating a lignocellulose-containing material.
The invention still further relates to a method of modifying blade grooves provided in a blade surface of a refiner blade or in a blade surface of a refiner blade segment for defibrating a lignocellulose-containing material.
Refiners for processing a fibrous material typically comprise two, but possibly also more, oppositely situated refiner blades, at least one of which is arranged to rotate around an axle such that the refiner blades turn with respect to one another. In disc refiners, the shape of the refiner blade is dislike, in cone refiners conical, and in cylinder refiners cylindrical.
The blade surfaces, i.e. refiner surfaces, of refiner blades for refiner discs typically consist of protrusions, i.e. blade bars, provided in the blade surface and blade grooves provided between the blade bars. Hereinafter, blade bars may also be called bars and blade grooves may also be called grooves. A refiner blade may consist of one uniform piece or of two or more blade segments arranged adjacent to one another, in which case the blade surfaces of the blade segments together form a uniform blade surface of the refiner blade.
Conventionally, both whole refiner blades and blade segments are manufactured by casting in sand moulds which are provided with forms that correspond with the blade bars and blade grooves in the blade surface of the refiner blade. When either whole refiner blades or blade segments are manufactured by casting, a problem is that in practice certain minimum size requirements which depend on the size of a casting piece exist for the size of the blade bars and blade grooves. A large casting piece cannot be provided with a blade pattern formed by blade bars and blade grooves that would be denser than a certain blade pattern, because molten metal would then not fill up the space for the blade bars in the mould, the result being an incomplete blade surface. The densest blade pattern to be arranged in a refiner blade of a disc refiner having a diameter of 1000 mm and a blade bar height of 10 mm and manufactured by casting in one piece, for instance, is presently a pattern wherein the minimum width of a blade bar is 3 mm and the minimum width of a groove is 4 mm. When a blade pattern denser than this is to be manufactured, a refiner blade has to be formed using blade segments, in which case casting enables a blade pattern to be achieved wherein with a 6 mm blade bar height the narrowest possible bar width is 1.6 mm and the narrowest possible groove width is 2 mm.
Blade surfaces of whole refiner blades or single blade segments may also be manufactured by welding or soldering blade bars into the body of a whole refiner blade or a blade segment. However, when manufacturing blades with a dense blade pattern, fastening of the blade bars requires a large amount of both manufacturing work to produce single blade bars and welding and soldering work in order to fasten them, which means that to manufacture a refiner blade is a time-consuming process even though it could at least partly be carried out automatically.
A further problem shared by all the manufacturing methods mentioned above is that prior to putting the refiner blade to use, the grooves and bars of the blade surface often also have to be finished off so as to remove e.g. welding or casting fins and sprues.